The landmark court decision in 1954 that declared segregation in public schools unconstitutional is Brown v. Board of Education. This Supreme Court case challenged the "separate but equal" doctrine established by Plessy v. Ferguson in 1896. The Court unanimously ruled that segregation in public education violated the Equal Protection Clause of the Fourteenth Amendment, stating that separate educational facilities are inherently unequal. This landmark decision not only overturned decades of legal precedent but also provided a significant impetus for the Civil Rights Movement, leading to further efforts to eliminate racial discrimination and promote equality in various public spheres across the United States.